Thermoplastic resins have a feature that they are plasticized and can be easily molded when they are heated to a temperature higher than the melting point or glass transition temperature of them. The reason of having many wide uses as compared with thermosetting resins is greatly due to the good shaping property or molding property.
However, in recent years, further improvement of molding property of the thermoplastic resins is required in the market and the improvement of molding property is an important problem in this field of the art.
One of reasons why widely used resins represented by polyolefins such as polyethylene, polypropylene, etc., styrene resins such as polystyrene, high impact polystyrene or styrene-acrylonitrile-butadiene copolymer, vinyl chloride resins and acryl resins can be used in great quantities and in wide uses is that they have good molding property and be easily shaped in addition to their performances.
In the field of widely used resins having such comparatively good molding property, further improvement of molding property has been required in recent years because of various uses. For example, production of moldings having a large size, a thin thickness or a complicated shape is a requirement of the age and, in any case, it is necessary to improve fluid property (improvement of molding property) of the resins.
Further, polyamide, polyoxymethylene, polyester (polybutylene terephthalate, polyethylene terephthalate, etc.), polycarbonate, polyphenylene ether, modified polyphenylene ether, polyarylate, polysulfone, polyether sulfone, polyphenylene sulfide, polyether ether ketone, etc. have been widely used as raw materials instead of metals, because of having strength and heat resistance, and use of them extends in the field of machinery components, parts for cars, parts for electric and electronic devices, etc. as engineering plastics.
Since these engineering plastics have high strength and high heat resistance but have a high melting point and a high melt viscosity, a high molding temperature and a high molding pressure are frequently required upon carrying out mold processing. Therefore, improvement of molding property is greatly required as compared with the case of widely used plastics.
As a technique of improving molding property of thes thermoplastic resins, a process in which intermolecular cohesive force of polymer is reduced by the following procedures is generally used.
(1) The polymer is modified by copolymerizing with a monomer having low polarity, in order to lower the polarity of the polymer. PA0 (2) Internal plasticization is accelerated by making branches in the polymer. PA0 (3) Degree of polymerization of the polymer is reduced. PA0 (4) Polymer having high fluidity such as low molecular weight polyethylene, ethylene-vinyl acetate copolymer, etc. is added. PA0 (5) A plasticizer is added. PA0 (1) In case of molding, namely, in a fluidized state of system, a fluidity improving agent becomes compatible with matrix components to show an effect of improving fluidity similar to plasticizers. PA0 (2) In case of using the molding, namely, in a state of stopping of fluidization [temperature range of lower than crystal melting point or Tg (glass transmission temperature) of the matrix], the fluidity improving agent causes phase separation from the matrix components and does not reduce Tg of the matrix. PA0 (a) low molecular compounds having a moiety compatible with matrix component upon molding, namely, in a molten state so as to act as platicizers, PA0 (b) compounds which cause phase separation from the matrix by crystallization at a temperature of below the molding temperature (below the glass transition temperature of the matrix), PA0 (c) compounds which are desired to have a comparatively strong polarity so as to ensure crystallization at a temperature of below the molding temperature, which have a unit having an affinity for matrix component so as to hold interfacial adhesive strength with the matrix even if phase separation occurs by crystallization,
However, in these procedures, there are still many problems of requiring improvement, which are important technical subjects. For example, in procedures (1) and (2), inherent characteristics (for example, heat resistance) of the resin are frequently damaged by modification such as by copolymerization, etc. In procedures (3) and (4), mechanical strength of the polymer is frequently reduced. In procedure (5), molding property (fluidity) is improved at the sacrifice of heat resistance of the polymer.
The present inventors have thought that the systme is preferred to be in the following state in order to produce moldings in which reduction of mechanical strength and deterioration of heat resistance are prevented, in an excellent state of molding.
As a result of studies in the above described view-point, a technique of using the following diamide compounds has been developed and filed already (Japanese Patent Application (OPI) No. 124950/84, U.S. Pat. No. 4,350,952 issued July 23, 1985, European Patent Application No. 88308004.7). ##STR1## wherein R.sup.1, R.sup.2 and R.sup.3 each represents a saturated or unsaturated straight chain or branched chain hydrocarbon residue having from 1 to 10 carbon atoms, an alicyclic hydrocarbon residue, an aromatic hydrocarbon residue, or a residue of derivatives of them.
The present invention has been attained by further developing the above described technique.